/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkSVGRenderContext_DEFINED
#define SkSVGRenderContext_DEFINED

#include "include/core/SkFontMgr.h"
#include "include/core/SkM44.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPath.h"
#include "include/core/SkRect.h"
#include "include/core/SkSize.h"
#include "include/core/SkTypes.h"
#include "modules/skresources/include/SkResources.h"
#include "modules/svg/include/SkSVGAttribute.h"
#include "modules/svg/include/SkSVGIDMapper.h"
#include "src/base/SkTLazy.h"
#include "src/core/SkTHash.h"

class SkCanvas;
class SkSVGLength;

class SK_API SkSVGLengthContext {
public:
    SkSVGLengthContext(const SkSize &viewport, SkScalar dpi = 90) : fViewport(viewport), fDPI(dpi) {}

    enum class LengthType {
        kHorizontal,
        kVertical,
        kOther,
    };

    const SkSize &viewPort() const
    {
        return fViewport;
    }
    void setViewPort(const SkSize &viewport)
    {
        fViewport = viewport;
    }

    SkScalar resolve(const SkSVGLength &, LengthType) const;
    SkRect resolveRect(const SkSVGLength &x, const SkSVGLength &y, const SkSVGLength &w, const SkSVGLength &h) const;

private:
    SkSize fViewport;
    SkScalar fDPI;
};

struct SK_API SkSVGPresentationContext {
    SkSVGPresentationContext();
    SkSVGPresentationContext(const SkSVGPresentationContext &) = default;
    SkSVGPresentationContext &operator = (const SkSVGPresentationContext &) = default;

    const skia_private::THashMap<SkString, SkSVGColorType> *fNamedColors = nullptr;

    // Inherited presentation attributes, computed for the current node.
    SkSVGPresentationAttributes fInherited;
};

class SK_API SkSVGRenderContext {
public:
    // Captures data required for object bounding box resolution.
    struct OBBScope {
        const SkSVGNode *fNode;
        const SkSVGRenderContext *fCtx;
    };

    SkSVGRenderContext(SkCanvas *, const sk_sp<SkFontMgr> &, const sk_sp<skresources::ResourceProvider> &,
        const SkSVGIDMapper &, const SkSVGLengthContext &, const SkSVGPresentationContext &, const OBBScope &);
    SkSVGRenderContext(const SkSVGRenderContext &);
    SkSVGRenderContext(const SkSVGRenderContext &, SkCanvas *);
    // Establish a new OBB scope.  Normally used when entering a node's render scope.
    SkSVGRenderContext(const SkSVGRenderContext &, const SkSVGNode *);
    ~SkSVGRenderContext();

    const SkSVGLengthContext &lengthContext() const
    {
        return *fLengthContext;
    }
    SkSVGLengthContext *writableLengthContext()
    {
        return fLengthContext.writable();
    }

    const SkSVGPresentationContext &presentationContext() const
    {
        return *fPresentationContext;
    }

    SkCanvas *canvas() const
    {
        return fCanvas;
    }
    void saveOnce();

    enum ApplyFlags {
        kLeaf = 1 << 0, // the target node doesn't have descendants
    };
    void applyPresentationAttributes(const SkSVGPresentationAttributes &, uint32_t flags);

    // Scoped wrapper that temporarily clears the original node reference.
    class BorrowedNode {
    public:
        explicit BorrowedNode(sk_sp<SkSVGNode> *node) : fOwner(node)
        {
            if (fOwner) {
                fBorrowed = std::move(*fOwner);
                *fOwner = nullptr;
            }
        }

        ~BorrowedNode()
        {
            if (fOwner) {
                *fOwner = std::move(fBorrowed);
            }
        }

        const SkSVGNode *get() const
        {
            return fBorrowed.get();
        }
        const SkSVGNode *operator->() const
        {
            return fBorrowed.get();
        }
        const SkSVGNode &operator*() const
        {
            return *fBorrowed;
        }

        explicit operator bool() const
        {
            return !!fBorrowed;
        }

    private:
        // noncopyable
        BorrowedNode(const BorrowedNode &) = delete;
        BorrowedNode &operator = (BorrowedNode &) = delete;

        sk_sp<SkSVGNode> *fOwner;
        sk_sp<SkSVGNode> fBorrowed;
    };

    // Note: the id->node association is cleared for the lifetime of the returned value
    // (effectively breaks reference cycles, assuming appropriate return value scoping).
    BorrowedNode findNodeById(const SkSVGIRI &) const;

    SkTLazy<SkPaint> fillPaint() const;
    SkTLazy<SkPaint> strokePaint() const;

    SkSVGColorType resolveSvgColor(const SkSVGColor &) const;

    // The local computed clip path (not inherited).
    const SkPath *clipPath() const
    {
        return fClipPath.getMaybeNull();
    }

    const sk_sp<skresources::ResourceProvider> &resourceProvider() const
    {
        return fResourceProvider;
    }

    sk_sp<SkFontMgr> fontMgr() const
    {
        // It is probably an oversight to try to render <text> without having set the SkFontMgr.
        // We will assert this in debug mode, but fallback to an empty fontmgr in release builds.
        SkASSERT(fFontMgr);
        return fFontMgr ? fFontMgr : SkFontMgr::RefEmpty();
    }

    // Returns the translate/scale transformation required to map into the current OBB scope,
    // with the specified units.
    struct OBBTransform {
        SkV2 offset, scale;
    };
    OBBTransform transformForCurrentOBB(SkSVGObjectBoundingBoxUnits) const;

    SkRect resolveOBBRect(const SkSVGLength &x, const SkSVGLength &y, const SkSVGLength &w, const SkSVGLength &h,
        SkSVGObjectBoundingBoxUnits) const;

private:
    // Stack-only
    void *operator new(size_t) = delete;
    void *operator new(size_t, void *) = delete;
    SkSVGRenderContext &operator = (const SkSVGRenderContext &) = delete;

    void applyOpacity(SkScalar opacity, uint32_t flags, bool hasFilter);
    void applyFilter(const SkSVGFuncIRI &);
    void applyClip(const SkSVGFuncIRI &);
    void applyMask(const SkSVGFuncIRI &);

    SkTLazy<SkPaint> commonPaint(const SkSVGPaint &, float opacity) const;

    const sk_sp<SkFontMgr> &fFontMgr;
    const sk_sp<skresources::ResourceProvider> &fResourceProvider;
    const SkSVGIDMapper &fIDMapper;
    SkTCopyOnFirstWrite<SkSVGLengthContext> fLengthContext;
    SkTCopyOnFirstWrite<SkSVGPresentationContext> fPresentationContext;
    SkCanvas *fCanvas;
    // The save count on 'fCanvas' at construction time.
    // A restoreToCount() will be issued on destruction.
    int fCanvasSaveCount;

    // clipPath, if present for the current context (not inherited).
    SkTLazy<SkPath> fClipPath;

    // Deferred opacity optimization for leaf nodes.
    float fDeferredPaintOpacity = 1;

    // Current object bounding box scope.
    const OBBScope fOBBScope;
};

#endif // SkSVGRenderContext_DEFINED
